| Autor: |
Frandsen J; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark., Pistoljevic N; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark., Quesada JP; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark., Amaro-Gahete FJ; Department of Physiology, University of Granada, Granada, Spain., Ritz C; Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark., Larsen S; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.; Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland., Dela F; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.; Department of Geriatrics, Bispebjerg University Hospital, Copenhagen, Denmark., Helge JW; Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. |
| Abstrakt: |
Female sex hormones fluctuate in a predictable manner throughout the menstrual cycle in eumenorrheic women. In studies conducted in both animal and humans, estrogen and progesterone have been found to exert individual metabolic effects during both rest and exercise, suggesting that estrogen may cause an increase in fat oxidation during exercise. However, not all studies find these metabolic changes with the natural physiological variation in the sex hormones. To date, no studies have investigated whether whole body peak fat oxidation rate (PFO) and maximal fat oxidation intensity (FAT max ) are affected at different time points [mid-follicular (MF), late-follicular (LF), and mid-luteal (ML)] in the menstrual cycle, where plasma estrogen and progesterone are either at their minimum or maximum. We hypothesized that an increased plasma estrogen concentration together with low progesterone concentration in LF would result in a modest but significant increase in PFO. We found no differences in body weight, body composition, or peak oxygen uptake (V̇o 2peak ) between any of the menstrual phases in the 19 healthy, young eumenorrheic women included in this study. PFO [MF: 0.379 (0.324-0.433) g/min; LF: 0.375 (0.329-0.421) g/min; ML: 0.382 (0.337-0.442) g/min; mean ± (95% CI)] and resting plasma free fatty acid concentrations [MF: 392 (293-492) µmol/l; LF: 477 (324-631) µmol/l; ML: 396 (285-508) µmol/L] were also similar across the menstrual cycle phases. Contrary to our hypothesis, we conclude that the naturally occurring fluctuations in the sex hormones estrogen and progesterone do not affect the whole body PFO and FAT max in young eumenorrheic women measured during a graded exercise test. NEW & NOTEWORTHY Menstrual cycle phase does not affect the peak fat oxidation rate during a graded exercise test. Natural physiological fluctuations in estrogen do not increase peak fat oxidation rate. FAT max is not influenced by menstrual cycle phase in healthy, young eumenorrheic women. |
